Method and apparatus for transmitting and receiving data in hybrid automatic repeat request process

ABSTRACT

A method, performed by a user equipment (UE), of transmitting uplink data is provided. The method includes receiving, from a base station, configuration information for an uplink resource; determining a Hybrid Automatic Repeat Request (HARQ) process based on the configuration information; starting a configured grant timer (CGT) and a configured grant retransmission timer (CGRT) when uplink data corresponding to the HARQ process is transmitted; restarting the CGRT when the uplink data corresponding to the HARQ process is retransmitted; receiving, from the base station, downlink feedback information (DFI); and stopping the CGT and the CGRT based on the DFI indicating whether the base station received the uplink data.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of prior application Ser.No. 16/863,238, filed on Apr. 30, 2020, which is based on and claimspriority under 35 U.S.C. § 119(a) of Korean patent application number10-2019-0051000, filed on Apr. 30, 2019, in the Korean IntellectualProperty Office, the disclosure of which is incorporated by referenceherein in its entirety.

BACKGROUND 1. Field

The disclosure relates to methods and apparatuses for transmitting andreceiving data in wireless communication systems.

2. Description of Related Art

To meet increasing demand with respect to wireless data traffic afterthe commercialization of 4^(th) generation (4G) communication systems,efforts have been made to develop 5^(th) generation (5G) or pre-5Gcommunication systems. For this reason, 5G or pre-5G communicationsystems are called ‘beyond 4G network’ communication systems or ‘postlong-term evolution (post-LTE)’ systems. To achieve high data rates,implementation of 5G communication systems in an ultra-high frequency ormillimeter-wave (mmWave) band (e.g., a 60 GHz band) is being considered.To reduce path loss of radio waves and increase a transmission distanceof radio waves in the ultra-high frequency band for 5G communicationsystems, various technologies such as beamforming, massivemultiple-input and multiple-output (massive MIMO), full-dimension MIMO(FD-MIMO), array antennas, analog beamforming, and large-scale antennas,are being studied. To improve system networks for 5G communicationsystems, various technologies such as evolved small cells, advancedsmall cells, cloud radio access networks (cloud RAN), ultra-densenetworks, device-to-device (D2D) communication, wireless backhaul,moving networks, cooperative communication, coordinated multi-points(CoMP), and interference cancellation, have also been developed. Inaddition, for 5G communication systems, advanced coding modulation (ACM)technologies such as hybrid frequency-shift keying (FSK) and quadratureamplitude modulation (QAM) (FQAM) and sliding window superpositioncoding (SWSC), and advanced access technologies such as filter bankmulti-carrier (FBMC), non-orthogonal multiple access (NOMA), and sparsecode multiple access (SCMA), have been developed.

The Internet has also evolved, from a human-based connection network,where humans create and consume information, to the Internet of things(IoT), where distributed elements such as objects exchange informationwith each other to process the information. In this regard, Internet ofEverything (IoE) technology has emerged, in which the IoT technology iscombined with, for example, technology for processing big data throughconnection with a cloud server. To implement the IoT, varioustechnological elements such as sensing technology, wired/wirelesscommunication and network infrastructures, service interface technology,and security technology are required and, in recent years, technologiesrelated to sensor networks for connecting objects, machine-to-machine(M2M) communication, and machine-type communication (MTC) have beenstudied. In the IoT environment, intelligent Internet technology (IT)services may be provided to collect and analyze data obtained fromconnected objects to create new value in human life. As existinginformation technology (IT) and various industries converge and combinewith each other, the IoT may be applied to various fields such as smarthomes, smart buildings, smart cities, smart cars or connected cars,smart grids, health care, smart home appliances, and advanced medicalservices.

Various attempts are being made to apply 5G communication systems to theIoT network. For example, technologies related to sensor networks, M2Mcommunication, and MTC, are being implemented by using 5G communicationtechnology including beamforming, MIMO, and array antennas. Applicationof a cloud RAN as the above-described big data processing technology isan example of convergence of 5G communication technology and IoTtechnology.

As various services may be provided according to the foregoing and thedevelopment of wireless communication systems, methods for smoothlyproviding such services are required.

The above information is presented as background information only, andto assist with an understanding of the disclosure. No determination hasbeen made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the disclosure.

SUMMARY

Aspects of the disclosure are to address at least the above-mentionedproblems and/or disadvantages, and to provide at least the advantagesdescribed below. Accordingly, an aspect of the disclosure is to provideapparatuses and methods capable of effectively providing services inwireless communication systems.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

In accordance with an aspect of the disclosure, a method, performed by auser equipment (UE), of transmitting uplink data is provided. The methodincludes receiving, from a base station, configuration information foran uplink resource; determining a Hybrid Automatic Repeat Request (HARQ)process based on the configuration information; starting a configuredgrant timer (CGT) and a configured grant retransmission timer (CGRT)when uplink data corresponding to the HARQ process is transmitted;restarting the CGRT when the uplink data corresponding to the HARQprocess is retransmitted; receiving, from the base station, downlinkfeedback information (DFI); and stopping the CGT and the CGRT based onthe DFI indicating whether the base station received the uplink data.

In accordance with an aspect of the disclosure, the CGT stops when theDFI indicates the base station received the uplink data.

In accordance with an aspect of the disclosure, the CGRT stops when theCGT expires.

In accordance with an aspect of the disclosure, the method furtherincludes receiving, from the base station, a dynamic grant, and thestarting of the CGT and the CGRT comprises starting the CGT based on thedynamic grant.

In accordance with an aspect of the disclosure, user equipment (UE) fortransmitting uplink data is provided. The UE includes a transceiver; andat least one processor coupled to the transceiver and configured to:receive, from a base station, configuration information for an uplinkresource; determine a Hybrid Automatic Repeat Request (HARQ) processbased on the configuration information; control to start a configuredgrant timer (CGT) and a configured grant retransmission timer (CGRT)when the uplink data corresponding to the HARQ process is transmitted;control to restart the CGRT when the uplink data corresponding to theHARQ process is retransmitted; receive, from the base station, downlinkfeedback information (DFI); and control to stop the CGT and the CGRTbased on the DFI indicating of whether the base station received theuplink data.

In accordance with an aspect of the disclosure, the at least oneprocessor is further configured to: receive, from the base station, adynamic grant; and control to start the CGT based on the dynamic grant.

In accordance with an aspect of the disclosure, a method, performed by abase station, of receiving uplink data is provided. The method includestransmitting, to user equipment (UE), configuration information for anuplink resource; receiving, from the UE, the uplink data correspondingto a Hybrid Automatic Repeat Request (HARQ) process, wherein the HARQprocess is determined based on the configuration information; andtransmitting, to the UE, downlink feedback information (DFI), wherein,based on the DFI, a configured grant timer (CGT) and a configured grantretransmission timer stop.

In accordance with an aspect of the disclosure, the method furtherincludes transmitting, to the UE, a dynamic grant, and wherein the CGTstarts based on the dynamic grant.

In accordance with an aspect of the disclosure, a base station fortransmitting uplink data is provided. The base station includes atransceiver; and at least one processor coupled to the transceiver andconfigured to: transmit, to user equipment (UE), configurationinformation for an uplink resource; and receive, from the UE, the uplinkdata corresponding to a Hybrid Automatic Repeat Request (HARQ) process,wherein the HARQ process is determined based on the configurationinformation; and transmit, to the UE, downlink feedback information(DFI), wherein, based on the DFI, a configured grant timer (CGT) and aconfigured grant retransmission stop.

In accordance with an aspect of the disclosure, the at least oneprocessor is further configured to transmit, to the UE, a dynamic grant,and wherein the CGT starts based on the dynamic grant.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the disclosure will be more apparent from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1A is a diagram illustrating a structure of a long-term evolution(LTE) system according to an embodiment of the disclosure;

FIG. 1B is a diagram illustrating a radio protocol architecture in LTEand new radio (NR) systems according to an embodiment of the disclosure;

FIG. 1C is a diagram describing listen-before-talk (LBT) Type 1according to an embodiment of the disclosure;

FIG. 1D is a diagram describing LBT Type 2 according to an embodiment ofthe disclosure;

FIG. 1E is a diagram temporally illustrating that a user equipment (UE)transmits data on a configured uplink resource according to anembodiment of the disclosure;

FIG. 1F is another diagram temporally illustrating that a UE transmitsdata on a configured uplink resource according to an embodiment of thedisclosure;

FIG. 1G is a flowchart illustrating an operation sequence when a UEtransmits data on a configured uplink resource according to anembodiment of the disclosure;

FIG. 1H is a block diagram of a UE in a wireless communication systemaccording to an embodiment of the disclosure;

FIG. 2A illustrates a radio bearer performing packet duplicationtransmission in a wireless communication system according to anembodiment of the disclosure;

FIG. 2B illustrates a method of calculating a measurement value of aradio link control (RLC) entity according to an embodiment of thedisclosure;

FIG. 2C illustrates another method of calculating a measurement value ofan RLC entity according to an embodiment of the disclosure;

FIG. 2D illustrates a method of calculating a measurement value of aradio bearer according to an embodiment of the disclosure;

FIG. 2E illustrates another method of calculating a measurement value ofa radio bearer according to an embodiment of the disclosure;

FIG. 2F is a flowchart illustrating a method of a UE performingspontaneous packet duplication transmission according to an embodimentof the disclosure;

FIG. 2G is another flowchart illustrating a method of a UE performingspontaneous packet duplication transmission according to an embodimentof the disclosure;

FIG. 2H illustrates a method of configuring spontaneous packetduplication transmission of a UE according to an embodiment of thedisclosure;

FIG. 2I illustrates a procedure of notifying a packet duplicationactivation state of a terminal according to an embodiment of thedisclosure;

FIG. 2J illustrates a procedure of triggering a regular buffer statusreport (BSR) according to spontaneous packet duplication activation of aUE according to an embodiment of the disclosure;

FIG. 2K is a flowchart illustrating a method of a UE performingspontaneous packet duplication transmission according to an embodimentof the disclosure;

FIG. 2L illustrates a split bearer operation when packet duplicationtransmission is deactivated according to an embodiment of thedisclosure;

FIG. 2M is a block diagram illustrating a structure of a base stationaccording to an embodiment of the disclosure; and

FIG. 2N is a block diagram illustrating a structure of a UE according toan embodiment of the disclosure.

Throughout the drawings, like reference numerals will be understood torefer to like parts, components, and structures.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding, but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein can be made without departing from the scope and spirit of thedisclosure. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but are merely used to enable aclear and consistent understanding of the disclosure. Accordingly, itshould be apparent to those skilled in the art that the followingdescription of various embodiments of the disclosure is provided forillustration purpose only, and not for the purpose of limiting thedisclosure as defined by the appended claims and their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

Throughout the disclosure, the expression “at least one of a, b or c”indicates only a, only b, only c, both a and b, both a and c, both b andc, all of a, b, and c, or variations thereof.

Examples of a terminal may include a user equipment (UE), a mobilestation (MS), a cellular phone, a smartphone, a computer, a multimediasystem capable of performing a communication function, or the like.

In the disclosure, a controller may also be referred to as at least oneprocessor.

Throughout the specification, a layer (or a layer apparatus) may also bereferred to as an entity.

In the following description, terms for identifying access nodes, termsreferring to network entities, terms referring to messages, termsreferring to interfaces between network entities, terms referring tovarious identification information, and the like are illustrated forconvenience of description. Thus, the disclosure is not limited to theterms described below and other terms referring to objects havingequivalent technical meanings may be used.

Hereinafter, for convenience of description, the disclosure may useterms and names defined in long-term evolution (LTE) and new radio (NR)standards that are the latest standards defined by the 3rd GenerationPartnership Project (3GPP) group among the current communicationstandards. However, the disclosure is not limited to those terms andnames, and may also be similarly applied to systems according to otherstandards. Particularly, the disclosure may be applied to 3GPP NR (5Gmobile communication standards).

FIG. 1A is a diagram illustrating a structure of an LTE system accordingto an embodiment of the disclosure. An NR system may have a similarstructure.

Referring to FIG. 1A, a wireless communication system may include aplurality of base stations 1 a-05, 1 a-10, 1 a-15, and 1 a-20, amobility management entity (MME) 1 a-25, and a serving-gateway (S-GW) 1a-30. A user terminal (e.g., a user equipment (UE) or a terminal) 1 a-35may access an external network through the base stations 1 a-05, 1 a-10,1 a-15, and 1 a-20 and the S-GW 1 a-30.

The base stations 1 a-05, 1 a-10, 1 a-15, and 1 a-20 may provide radioaccess to terminals accessing the network as access nodes of a cellularnetwork. That is, in order to service traffic of users, based on stateinformation such as buffer status of UEs, available transmission powerstatus, and/or channel status, the base stations 1 a-05, 1 a-10, 1 a-15,and 1 a-20 may perform scheduling and support connection between UEs anda core network (CN). The MME 1 a-25 may be an entity performing variouscontrol functions as well as a mobility management function for a UE andmay be connected to a plurality of base stations, and the S-GW 1 a-30may be an entity providing a data bearer. Also, the MME 1 a-25 and theS-GW 1 a-30 may perform authentication, bearer management, or the like,for the UE accessing the network and may process packets received fromthe base stations 1 a-05, 1 a-10, 1 a-15, and 1 a-20, or packets to betransmitted to the base stations 1 a-05, 1 a-10, 1 a-15, and 1 a-20.

FIG. 1B is a diagram illustrating a radio protocol architecture in LTEand NR systems according to an embodiment of the disclosure.

Referring to FIG. 1B, the radio protocol of the LTE system may includePacket Data Convergence Protocol (PDCP) 1 b-05 and 1 b-40, Radio LinkControl (RLC) 1 b-10 and 1 b-35, and Medium Access Control (MAC) 1 b-15and 1 b-30 in a UE and an eNB, respectively. The PDCP 1 b-05 and 1 b-40may perform Internet Protocol (IP) header compression/decompression orthe like, and the RLC 1 b-10 and 1 b-35 may reconstruct a PDCP packetdata unit (PDU) in a suitable size. The MAC 1 b-15 and 1 b-30 may beconnected to several RLC layers configured in one UE and may perform anoperation of multiplexing RLC PDUs into MAC PDUs and demultiplexing RLCPDUs from MAC PDUs. Physical layers (PHY) 1 b-20 and 1 b-25 maychannel-code and modulate data of a higher layer, generate orthogonalfrequency division multiplexing (OFDM) symbols, and transmit the same onradio channels, or may demodulate and channel-decode OFDM symbolsreceived on radio channels and transmit the result thereof to the higherlayer. Also, the physical layer may also use a hybrid ARQ (HARQ) foradditional error correction, and a receiving end may transmitinformation about whether the packet transmitted by a transmitting endis received, in 1 bit. This may be referred to as HARQ ACK/NACKinformation. In the case of LTE, downlink HARQ ACK/NACK informationabout uplink data transmission may be transmitted by using a physicalhybrid-ARQ indicator channel (PHICH) physical channel, and in the caseof NR, it may be determined whether retransmission is required or newtransmission should be performed through scheduling information of theUE in a physical downlink control channel (PDCCH) that is a channel onwhich downlink/uplink resource allocation or the like is transmitted.This may be because NR applies an asynchronous HARQ.

Information included in the scheduling information of the PDCCH mayinclude HARQ process identifier (ID), new data indicator (NDI),redundancy version identifier (RVID), or the like. The HARQ process ID(HARQ process identifier) may be transmitted to support a HARQ operationin parallel; for example, in the case of downlink data transmission,even when the ACK of the corresponding data has not yet been receivedafter “HARQ process ID=1” is transmitted, new data having HARQ processID=2 may be scheduled. In the case of NR, 16 HARQ process IDs may besupported in the uplink. Also, a new data indicator (NDI) may be used toindicate whether the corresponding data is new data. For example, in thecase of downlink transmission, a base station may indicate newtransmission when an NDI value is 0 for a particular HARQ process IDvalue and may indicate retransmission when it is 1. Alternatively, itmay indicate new retransmission or transmission depending on whether thevalue itself is equal to or different from the previous value. Aredundancy version (RV) may be information indicating which packet amonga plurality of duplicate packets generated for retransmission thecorresponding packet transmits in the case of packet retransmission.

Uplink HARQ ACK/NACK information about downlink data transmission may betransmitted by using a physical uplink control channel (PUCCH) or aphysical uplink shared channel (PUSCH) physical channel.

The PUCCH may be generally transmitted in the uplink of a primary cell(PCell) described below; however, when it is supported by a UE, it maybe additionally transmitted to the UE in a secondary cell (SCell)described below, which may be referred to as a PUCCH SCell.

A radio resource control (RRC) layer (not illustrated) may exist abovethe PDCP layer of the UE and the base station, and the RRC layer maytransmit/receive connection and measurement-related control messages forradio resource control.

A PHY layer may include one frequency/carrier or a plurality offrequencies/carriers, and a technology of simultaneously configuring andusing a plurality of frequencies may be referred to as carrieraggregation (CA). The CA may mean a technology that may increase thetransmission amount by the number of secondary carriers by using oneprimary carrier and one secondary carrier or a plurality of secondarycarriers instead of using only one carrier for communication between aterminal (or UE) and a base station (evolved universal mobile telephonesystem (UMTS) terrestrial radio access network (E-UTRAN), Node B, orevolved Node B (eNB)). In LTE, a cell in a base station using a primarycarrier may be referred to as a main cell or a primary cell (PCell), anda cell in a base station using a secondary carrier may be referred to asa subcell or a secondary cell (SCell).

A scenario in which the above 5G system operates in an unlicensed bandmay be considered. This system may be referred to as NR-U. Also, theunlicensed band may mean a frequency band that anyone may freely usewithout a separate license within the regulatory permission at acorresponding frequency. For example, the unlicensed band may include a2.4 GHz or 5 GHz band, and wireless LAN, Bluetooth, or the like mayperform communication by using the corresponding frequency.

In order to perform communication in the unlicensed band, data should betransmitted or received according to the regulation established by eachcountry. In more detail, according to the regulation, before acommunication device (e.g., base station and UE) transmits in theunlicensed band, the communication device should ‘listen’ to determinewhether the unlicensed band is occupied by another communication deviceand then perform ‘transmission’ when the unlicensed band is determinedas being unoccupied. Such a method of listening and then transmittingwhen the unlicensed band is unoccupied may be referred to aslisten-before-talk (LBT). A regulation may be established to perform LBTin each country and unlicensed band, and a communication device shouldperform LBT according to the regulation when communicating in theunlicensed band.

In general, there may be two types of LBT, Type 1 and Type 2.

FIG. 1C is a diagram describing LBT Type 1 according to an embodiment ofthe disclosure.

Referring to FIG. 1C, LBT Type 1 may be a method of randomly determininga time for listening to whether other peripheral devices transmit beforetransmission, and then transmitting when the channel is unoccupied forthe random time. In this case, it may first listen for a fixed timeT_(d), and then, when the channel is unoccupied, it may determinewhether the channel is unoccupied for a random time N.

In this case, it may be differentially determined how to determine thevalues of T_(d) and N according to the priority and importance oftraffic, and there may be a total of four different classes. The classmay be referred to as a channel access priority class (CAPC).

Also, according to the CAPC, it may have a time length ofT_(d)=16+m_(p)*9 (μs) and have N=random (0, CW_(p))*9 (μs), and the CWvalue may start from CW_(min,p) and increase about twice whenevertransmission fails and may have a maximum value of CW_(max,p). Forexample, when LBT is performed by using a CAPC of 3, T_(d) may have alength of 16+3*9=43 μs and N may have a random value selected between 0and 15 in the case of initial transmission, and for example, when 7 isselected as CW_(p), N may be 7*9=63 μs and thus the communication devicemay transmit data when the channel is unoccupied for 106 μs.

TABLE 1 Channel Access Priority Class allowed (CAPC) (p) m_(p)CW_(min, p) CW_(max, p) T_(m cot, p) CW_(p) sizes 1 1 3 7 2 ms {3, 7} 21 7 15 3 ms {7, 15} 3 3 15 63 8 or 10 ms {15, 31, 63} 4 7 15 1023 8 or10 ms {15, 31, 63, 127, 255, 511, 1023}

In the above example (when 7 is selected as CW_(p) for N), when it isdetermined that the channel has been occupied by another device (i.e.,when a received signal strength indicator (RSSI) is more than or equalto a certain threshold value) in the middle of determining whether thechannel is unoccupied (e.g., when CW_(p) has passed by 3 out of 7 andremains by 4), the UE may wait until the occupancy of the channel endsand then wait for T_(d) again, and then perform transmission bydetermining whether the channel is unoccupied for the remaining time of4. As shown in Table 1, an LBT method with a low CAPC may be used totransmit high-priority traffic.

When the communication device determines that the channel is unoccupiedand thus occupies the channel once, the maximum time during which thecommunication device may occupy the channel may be referred to asT_(mcot,p). That is, the maximum time during which the UE may occupy thechannel may be restricted according to the CAPC value. For example, inthe case of CAPC=1 having a high priority, the probability of occupyingthe channel may be high, while the time during which the channel may beoccupied may be relatively short. When the CAPC is 3 or 4, a long value(i.e., 10 ms) may be used only when there is no heterogeneous devicesuch as a wireless LAN.

FIG. 1D is a diagram describing LBT Type 2 according to an embodiment ofthe disclosure.

Referring to FIG. 1D, LBT Type 2 may be a method of fixing a time forlistening to whether other peripheral devices transmit beforetransmission, and transmitting immediately when the channel isunoccupied for the fixed time. That is, referring to FIG. 1D, when thecommunication device needs to transmit, it may listen to (sense) thechannel for a fixed time of T_(short) (=T_(f)+T_(s)) and then transmitdata immediately when it is determined that the channel is unoccupied.This may be an LBT method that may be used to transmit a signal with avery high priority. Accordingly, a random-access preamble, a PUCCH, orthe like may be a signal with a high importance and may be transmittedby using the LBT method of FIG. 1D.

When the base station dynamically allocates a resource for transmittingdownlink data and transmits the downlink data, the base station maydetermine the LBT Type and the CAPC according to the type of data to betransmitted. Also, when the base station dynamically allocates aresource for transmitting uplink data and the UE transmits data to thebase station on the resource, the base station may determine the LBTType and the CAPC to be used by the UE to transmit data and indicate thesame to the UE. That is, when the base station transmits uplink resourceallocation information to the UE on the PDCCH, the LBT type and the CAPCmay be indicated to transmit uplink data. In addition, when the basestation determines that the UE does not need to perform LBT, it mayindicate not to perform LBT. For example, in the TDD system wheredownlink and uplink frequencies are equal to each other, when the basestation occupies the channel once, and the switching time between thedownlink and the uplink is very short, the UE may not need to performLBT by assuming that the base station continues to occupy the channel.For example, when the base station occupies the channel once by usingCAPC=4, it may be assumed that the base station occupies the channel inboth the downlink and the uplink for 8 ms or 10 ms, and the UEtransmitting data during the corresponding section may not need toperform LBT. In this case, when the base station schedules the uplink tothe UE, it may separately indicate that LBT may not need to beperformed. Alternatively, when the base station allocates an uplinkresource to the UE, when it is determined that the uplink of the UE isto be always allocated in the T_(mcot,p) of the base station, it may beindicated to the UE through a message of the RRC layer (e.g., anRRCReconfiguration message) that LBT may not need to be performed, andboth the LBT type and the CAPC may be omitted in the uplink resourceallocation in the PDCCH transmitted to the UE.

Also, a method of allocating a periodic resource instead of dynamicallyallocating a resource for uplink transmission at every time may be used,and such a periodic resource may be referred to as a configured (uplink)grant.

Although not illustrated in the disclosure, in the configured grant usedin the licensed band, each periodic resource may be mapped to aparticular HARQ process ID and only new data may be transmitted on theperiodic resource, and when retransmission is required, the base stationmay separately and dynamically allocate a resource to the UE to performretransmission.

The base station may also perform the above operation in the unlicensedband, and when a periodic resource is mapped to a particular HARQprocess ID and restricted to transmit only new data as in the licensedband, the corresponding packet may not be transmitted for some time whenthe UE fails while performing LBT to transmit data on the correspondingresource. In order to solve this, instead of a periodic resource beingmapped to a particular HARQ process ID and restricted to transmit onlynew data as in the licensed band, a HARQ process ID to be transmittedfor each periodic resource and whether it is new transmission orretransmission may be separately indicated under the determination ofthe UE. This may be to allow the base station to determine which datahas been received, by together transmitting information about the HARQprocess ID, the NDI, and the RVID (hereinafter collectively referred toas UCI) described above, in the PUSCH resource transmitting data, whenthe UE transmits data on the corresponding resource.

FIG. 1E is a diagram temporally illustrating that a UE transmits data ona configured uplink resource according to an embodiment of thedisclosure.

Referring to FIG. 1E, a situation in which the UE is in an RRCconnection state (RRC_CONNECTED) by accessing the base station isassumed. Also, a scenario in which the UE is allocated an uplinkresource 1 e-01 configured to enable periodic uplink transmission, fromthe base station is assumed. A periodic uplink resource may correspondto a configured grant in the unlicensed band described above (that is,the UE determines data to be transmitted and transmits the sameincluding UCI information); however, the periodic uplink resource itselfmay not necessarily need to operate in the unlicensed band.

In 1 e-00, when uplink data transmission is required, the UE may firstperform LBT before transmitting data on the corresponding periodicresource 1 e-01 and then transmit data in the uplink when succeeding inthe LBT (1 e-03). In this case, the UE may allow the base station todecode the corresponding data afterward by notifying which HARQ processID the corresponding transmission belongs to, whether the correspondingtransmission is new transmission (e.g., NDI=0), and which value atransmitted RV value is. Also, when the UE succeeds in the transmission,the UE may drive two types of timers.

A first timer may be referred to as a configured grant timer (CGT) (1e-15), and the first timer may ensure the performance of retransmissionby preventing the UE from performing new transmission on thecorresponding HARQ process ID while the first timer is running. Theexpiration of the first timer may mean that the base station hassuccessfully received the corresponding data and new transmission may beperformed with the corresponding HARQ process ID.

A second timer may be referred to as a configured grant retransmissiontimer (CGRT) (1 e-11) (1 e-13), and the second timer may be to restrictretransmission such that that the base station may determine thereception or not while the second timer is running. The expiration ofthe second timer may mean that the base station has failed to receivethe corresponding data and thus the corresponding data may beretransmitted.

Accordingly, the UE may perform initial transmission (1 e-03) and thendrive the CGT and the CGRT, and when failing to receive downlinkfeedback information (DFI) indicating that data has been successfullyreceived from the base station until the CGRT expires, the UE maydetermine that the corresponding data has not been successfullytransmitted, and then perform retransmission of the corresponding dataand accordingly, may perform retransmission on a periodic uplinkresource (1 e-05) and drive the CGRT again (1 e-13). Upon successfullyreceiving the corresponding data, the base station may transmit DFI tothe UE to notify the UE that the corresponding data has beensuccessfully received (1 e-21), and upon receiving the DFI, the UE maydetermine that the corresponding data has been successfully transmittedand stop driving the CGRT because the CGRT need no longer be running (1e-23). Thereafter, when the CGT expires (1 e-25), the UE may alsotransmit new data by using the corresponding HARQ process ID.

Likewise, in 1 e-50, when uplink data transmission is required, the UEmay first perform LBT before transmitting data on a correspondingperiodic resource 1 e-51 and then transmit data in the uplink whensucceeding in the LBT (1 e-53). In this case, the UE may allow the basestation to decode the corresponding data afterward by notifying whichHARQ process ID the corresponding transmission belongs to, whether thecorresponding transmission is new transmission (e.g., NDI=0), and whichvalue a transmitted RV value is. Also, as in the above description, whensucceeding in the transmission, the UE may drive two types of timers,that is, a CGT (1 e-65) and a CGRT (1 e-61).

Thereafter, when failing to receive DFI indicating that data has beensuccessfully received from the base station until the CGRT expires, theUE may determine that the corresponding data has not been successfullytransmitted and then perform retransmission of the corresponding data,and accordingly, may perform retransmission on a periodic uplinkresource (1 e-55) and drive the CGRT again (1 e-63). Although the basestation has not correctly received the corresponding data, the basestation may no longer leave it to the UE and may directly anddynamically allocate a resource to perform retransmission. For thispurpose, the base station may indicate to the UE retransmission on thecorresponding HARQ process ID by using the PDCCH (1 e-71). Uponreceiving this, the UE may stop the CGRT managed for retransmission inthe configured grant (1 e-73) and restart the CGT (1 e-75). Accordingly,the UE may retransmit the corresponding data according to the uplinkresource allocation information received by using the PDCCH (1 e-81).Also, the UE may also restart the CGT when actual data has beentransmitted as well as when the PDCCH has been received (1 e-77).Accordingly, whenever a dynamic resource is scheduled from the basestation and whenever transmission is performed, the UE may restart thecorresponding CGT and may give all control to the base station.

FIG. 1F is another diagram temporally illustrating that a UE transmitsdata on a configured uplink resource according to an embodiment of thedisclosure.

Referring to FIG. 1F, as in FIG. 1E, a situation in which the UE is inan RRC connection state (RRC_CONNECTED) by accessing the base station isassumed. Also, a scenario in which an uplink resource configured toenable periodic uplink transmission is allocated from the base stationis assumed. A periodic uplink resource may correspond to a configuredgrant in the unlicensed band described above (that is, the UE determinesdata to be transmitted and transmits the same including UCIinformation); however, the periodic uplink resource itself may notnecessarily need to operate in the unlicensed band.

Accordingly, in 1 f-00, when uplink data transmission is required, theUE may first perform LBT before transmitting data on a correspondingperiodic resource 1 f-01 and then transmit data in the uplink whensucceeding in LBT (1 f-03). In this case, the UE may allow the basestation to decode the corresponding data afterward by notifying whichHARQ process ID the corresponding transmission belongs to, whether thecorresponding transmission is new transmission (e.g., NDI=0), and whichvalue a transmitted RV value is. Also, when succeeding in thetransmission, the UE may drive two types of timers, that is, a CGT (1f-15) and a CGRT (1 f-11).

Thereafter, when failing to receive DFI indicating that data has beensuccessfully received from the base station until the CGRT expires, theUE may determine that the corresponding data has not been successfullytransmitted, and then perform retransmission of the corresponding dataand accordingly, may perform retransmission on a periodic uplinkresource (1 f-05) and drive the CGRT again (1 f-13). Upon successfullyreceiving the corresponding data, the base station may transmit DFI tothe UE to notify the UE that the corresponding data has beensuccessfully received (1 f-21), and upon receiving the DFI, the UE maydetermine that the corresponding data has been successfully transmittedand stop driving the CGRT because the CGRT need no longer be running (1f-23). Also, because the corresponding data has been successfullyreceived, the UE may also terminate the CGT such that the correspondingHARQ process ID may be immediately used for new data transmission (1f-25). Accordingly, the UE may immediately transmit new data by usingthe corresponding HARQ process ID.

In 1 f-50, when uplink data transmission is required, the UE may firstperform LBT before transmitting data on a corresponding periodicresource 1 f-51 and then transmit data in the uplink when succeeding inthe LBT (1 f-53). In this case, the UE may allow the base station todecode the corresponding data afterward by notifying which HARQ processID the corresponding transmission belongs to, whether the correspondingtransmission is new transmission (e.g., NDI=0), and which value atransmitted RV value is. Also, when succeeding in the transmission, theUE may drive two types of timers, that is, a CGT (1 f-75) and a CGRT (1f-61).

Thereafter, when failing to receive DFI indicating that data has beensuccessfully received from the base station until the CGRT expires, theUE may determine that the corresponding data has not been successfullytransmitted and then perform retransmission of the corresponding data,and accordingly, may perform retransmission on a periodic uplinkresource (1 f-55) (1 f-57) and drive the CGRT again (1 f-63) (1 f-65).As illustrated in FIG. 1F, this may be repeated several times and may berepeated until the CGT expires (1 f-71). As described above, because theCGT is (re)started when the LBT has succeeded and thus data is actually(re)transmitted, when the CGT has expired, it may be determined that thebase station has successfully received data, and accordingly, the CGRT,which has been running, may also be stopped (1 f-67). Accordingly, theUE may immediately transmit new data by using the corresponding HARQprocess ID.

FIG. 1G is a flowchart illustrating an operation sequence when a UEtransmits data on a configured uplink resource according to anembodiment of the disclosure.

Referring to FIG. 1G, a situation in which the UE is in an RRCconnection state (RRC_CONNECTED) by accessing the base station isassumed.

The UE may receive a configured uplink resource (configured uplinkgrant) configured to enable periodic uplink transmission, from the basestation at operation 1 g-03. A periodic uplink resource may correspondto a configured grant in the unlicensed band described above (that is,the UE determines data to be transmitted and transmits the sameincluding UCI information); however, the periodic uplink resource itselfmay not necessarily need to operate in the unlicensed band.

Accordingly, the UE may determine how to transmit (RV) data by whichHARQ process ID whenever each periodic uplink resource arrives atoperation 1 g-05, and accordingly, may attempt to transmit the data onthe corresponding resource at operation 1 g-07. In FIG. 1G, an operationin the unlicensed band is assumed, and accordingly, actual transmissionmay be determined according to the success or failure of UL LBT. Whenhaving failed in the UL LBT at operation 1 g-09, the UE may attempt totransmit the corresponding data on the configured grant resource of thenext period. When having succeeded in the UL LBT at operation 1 g-09,depending on whether the corresponding transmission is initialtransmission at operation 1 g-11, when the corresponding transmission isinitial transmission, the UE may start the CGT at operation 1 g-13, andotherwise (that is, when the corresponding transmission isretransmission), the UE may start or restart the CGRT at operation 1g-15.

Thereafter, the UE may receive the DFI from the base station or may bedynamically scheduled for retransmission on the PDCCH at operation 1g-17.

When having received the DFI at operation 1 g-19 (that is, when havingreceived ACK information on the corresponding data), the UE may stop theCGRT that has been running and also stop the CGT at operation 1 g-21 totransmit new data by the corresponding HARQ process ID at operation 1g-05.

When the UE performs retransmission by dynamically receiving resourceallocation from the base station on the PDCCH, the UE may transmit databy (re)starting the CGT whenever receiving the PDCCH and transmittingactual data at operation 1 g-23. From this time, the UE may pass allcontrol of resource allocation to the base station, and accordingly,when the CGT expires at operation 1 g-35, the UE may determine that thecorresponding data has been successfully transmitted and transmit newdata by the corresponding HARQ process ID at operation 1 g-05. In thiscase, because the CGRT is not running, it may be unnecessary to stop theCGRT separately.

When the UE fails to receive the DFI from the base station or when theCGRT expires in the state where the retransmission is not dynamicallyscheduled on the PDCCH at operation 1 g-31, the UE may consider that thebase station has failed to receive the corresponding data and thus mayretransmit the corresponding data on a periodic resource at operation 1g-33 and accordingly may select the corresponding data to be transmittedon the periodic resource at operation 1 g-05.

When the CGT expires at operation 1 g-35, it is determined that thecorresponding data has been successfully transmitted, and when the CGRTis running, the CGRT may be stopped at operation 1 g-37 and the UE mayimmediately transmit new data by the corresponding HARQ process ID atoperation 1 g-05.

FIG. 1H is a block diagram of a UE in a wireless communication systemaccording to an embodiment of the disclosure.

Referring to FIG. 1H, the UE may include a radio frequency (RF)processor 1 h-10, a baseband processor 1 h-20, storage 1 h-30, and atleast one processor or controller 1 h-40.

The RF processor 1 h-10 may perform functions for transmitting orreceiving signals by using wireless channels, such as band conversionand amplification of signals. That is, the RF processor 1 h-10 mayup-convert a baseband signal provided from the baseband processor 1 h-20into an RF band signal and transmit the same through an antenna, and maydown-convert an RF band signal received through the antenna into abaseband signal. For example, the RF processor 1 h-10 may include atransmission filter, a reception filter, an amplifier, a mixer, anoscillator, a digital-to-analog converter (DAC), and ananalog-to-digital converter (ADC). Although only one antenna isillustrated in FIG. 1H, the UE may include a plurality of antennas.Also, the RF processor 1 h-10 may include a plurality of RF chains. Inaddition, the RF processor 1 h-10 may perform beamforming. Forbeamforming, the RF processor 1 h-10 may adjust the phase and magnitudeof each of the signals transmitted or received through a plurality ofantennas or antenna elements.

The baseband processor 1 h-20 may perform a conversion function betweena baseband signal and a bitstream according to the physical layerstandard of the system. For example, during data transmission, thebaseband processor 1 h-20 may generate complex symbols by encoding andmodulating a transmission bitstream. Also, during data reception, thebaseband processor 1 h-20 may restore a reception bitstream bydemodulating and decoding the baseband signal provided from the RFprocessor 1 h-10. For example, according to an OFDM scheme, during datatransmission, the baseband processor 1 h-20 may generate complex symbolsby encoding and modulating a transmission bitstream, map the complexsymbols to subcarriers, and then configure OFDM symbols through aninverse fast Fourier transform (IFFT) operation and cyclic prefix (CP)insertion. Also, during data reception, the baseband processor 1 h-20may divide a baseband signal provided from the RF processor 1 h-10 intoOFDM symbol units, restore signals mapped to the subcarriers through afast Fourier transform (FFT) operation, and then restore a receptionbitstream through demodulation and decoding.

The baseband processor 1 h-20 and the RF processor 1 h-10 may transmitand receive signals as described above. Accordingly, the basebandprocessor 1 h-20 and the RF processor 1 h-10 may be referred to as atransmitter, a receiver, a transceiver, or a communicator. In addition,at least one of the baseband processor 1 h-20 or the RF processor 1 h-10may include a plurality of communication modules to support a pluralityof different radio access technologies. Also, at least one of thebaseband processor 1 h-20 or the RF processor 1 h-10 may includedifferent communication modules to process signals of differentfrequency bands. For example, the different wireless access technologiesmay include wireless LAN (e.g., IEEE 802.11) and cellular network (e.g.,LTE). Also, the different frequency bands may include a super highfrequency (SHF) (e.g., 2.5 GHz or 5 GHz) band and a millimeter wave(e.g., 60 GHz) band.

The storage 1 h-30 may store data such as a basic program, anapplication program, or configuration information, for operation of theUE. Particularly, the storage 1 h-30 may store information related to awireless LAN node performing wireless communication by using thewireless LAN access technology. Also, the storage 1 h-30 may provide thestored data at the request of the controller 1 h-40.

The controller 1 h-40 may control overall operations of the UE. Forexample, the controller 1 h-40 may transmit or receive signals throughthe baseband processor 1 h-20 and the RF processor 1 h-10. Also, thecontroller 1 h-40 may write/read data into/from the storage 1 h-30. Forthis purpose, the controller 1 h-40 may include at least one processor.For example, the controller 1 h-40 may include a communication processor(CP) for performing control for communication and an applicationprocessor (AP) for controlling a higher layer such as an applicationprogram. According to an embodiment of the disclosure, the controller 1h-40 may include a multiple connection processor 1 h-42 performing aprocess for operating in a multiple connection mode. For example, thecontroller 1 h-40 may control the UE to perform the procedureillustrated in the operation of the UE illustrated in FIG. 1E.

According to an embodiment of the disclosure, the controller 1 h-40 maycontrol transmission by driving the CGT and the CGRT in order totransmit data in the uplink configured by the above methods.

FIG. 2A illustrates a radio bearer performing packet duplicationtransmission in a wireless communication system according to anembodiment of the disclosure.

Referring to FIG. 2A, a radio bearer (2 a-10) in which packetduplication transmission may be configured may include one packet dataconvergence protocol (PDCP) entity 2 a-20 and two or more radio linkcontrol (RLC) entities 2 a-30, 2 a-40, and 2 a-50. When packetduplication transmission is activated, the radio bearer may implementduplication transmission of the same packet by duplicating packets inthe PDCP entity 2 a-20 and transmitting each of the duplicated packetsto a plurality of RLC entities 2 a-30, 2 a-40, and 2 a-50 used in thepacket duplication transmission. The RLC entities 2 a-30, 2 a-40, and 2a-50 may be respectively transmitted by using logical channels 2 a-60, 2a-70, and 2 a-80 to a medium access control (MAC) layer to performtransmission. In this case, because the RLC entities 2 a-30, 2 a-40, and2 a-50 may have one-to-one correspondence with the logical channels 2a-60, 2 a-70, and 2 a-80, referring to a particular logical channel maymean an RLC entity corresponding to the logical channel. The logicalchannels 2 a-60, 2 a-70, and 2 a-80 may receive a list of availablecells from the base station. In FIG. 2A, it is assumed that the logicalchannel 1 (2 a-60) may use a cell 1 (2 a-90) and a cell 2 (2 a-100), thelogical channel 2 (2 a-70) may use a cell 4 (2 a-120), a cell 5 (2a-130), and a cell 6 (2 a-140), and the logical channel 3 (2 a-80) mayuse a cell 8 (2 a-160). In this example, cell 3 (2 a-110) and cell 7 (2a-150) are present, but unused.

A list of cells usable by each logical channel may be transmitted bybeing included in the logical channel configuration in an RRCconfiguration message that is transmitted from the base station to theUE. As described above, because the RLC entity and the logical channelmay have one-to-one correspondence with each other, a list of cellsusable by the logical channel may correspond to a list of cells usableby the RLC entity. The cells described in FIG. 2A may be cellsconfigured in the same cell group or in some cases, may be cellsconfigured in two or more cell groups. Also, among the RLC entitiesconfigured in the radio bearer, an RLC entity (2 a-30, 2 a-40, or 2a-50) and a primary RLC entity may be included. In this case, theprimary RLC may be used to transmit a PDCP control protocol data unit(PDU) or may be used to preferentially transmit a packet when packetduplication transmission is deactivated. Also, a secondary RLC entitymay be configured in the radio bearer. In this case, the secondary RLCentity may be used for a split bearer operation when packet duplicationtransmission is deactivated among the RLC entities configured in adifferent cell group than the primary RLC entity.

FIG. 2B illustrates a method of calculating a measurement value of anRLC entity according to an embodiment of the disclosure.

Referring to FIG. 2B, the activation and deactivation of packetduplication transmission may be configured by the base station. However,the activation and deactivation of packet duplication transmission bythe base station may take a long time until the base station recognizesthe state change of the UE and issues an activation or deactivationcommand to the UE. In addition, an additional delay time may occur whenthe UE does not accurately receive a packet duplication activation ordeactivate command. In order to reduce this inefficiency, the UE mayspontaneously perform packet duplication transmission according to aconfigured or preconfigured rule. This rule may be due to the result ofmeasuring a cell usable by the radio bearer performing packetduplication transmission. FIG. 2B illustrates a method of defining ameasurement value of an RLC entity (or a corresponding logical channel)used to perform spontaneous packet duplication transmission of the UE.In FIG. 2B, it is assumed that the cells usable by the logical channelare a cell 1 (2 b-30) and a cell 2 (2 b-40). Because the UE measures thechannel quality of both the cell 1 (2 b-30) and the cell 2 (2 b-40),these values may be used to derive a measurement value of the channelquality of an RLC entity 2 b-10 (or a corresponding logical channel 2b-20) (2 b-50). In this case, the measured value of the channel qualityof the RLC entity 2 b-10 (or the corresponding logical channel 2 b-20)may be one of the average value, the minimum value, the maximum value,and the median value of the measurement values of the cells usable bythe RLC entity 2 b-10. In this case, the usable cells may be configuredcells or activated cells among the configured cells. The measurementvalue of the channel quality mentioned in FIG. 2B may include one of areference signal received power (RSRP), a reference signal receivedquality (RSRQ), a signal-to-interference and noise ratio (SINR), and achannel quality indicator (CQI). Also, the measurement value may be avalue to which one or more of L1 filtering or L3 filtering are applied.

FIG. 2C illustrates another method of calculating a measurement value ofan RLC entity according to an embodiment of the disclosure.

Referring to FIG. 2C, the activation and deactivation of packetduplication transmission may be configured by the base station. However,the activation and deactivation of packet duplication transmission bythe base station may take a long time until the base station recognizesthe state change of the UE and issues an activation or deactivationcommand. In addition, an additional delay time may occur when the UEdoes not accurately receive a packet duplication activation ordeactivate command. In order to reduce this inefficiency, the UE mayspontaneously perform packet duplication transmission according to aconfigured or preconfigured rule. This rule may be due to the result ofmeasuring a cell usable by the radio bearer performing packetduplication transmission. FIG. 2C illustrates a method of defining ameasurement value of an RLC entity (or a corresponding logical channel)used to perform spontaneous packet duplication transmission of the UE.In FIG. 2C, it is assumed that the cells usable by the logical channelare a cell 1 (2 c-30) and a cell 2 (2 c-40). In this case, among thecells usable in an RLC entity 2 c-10, the channel quality of aconfigured or preconfigured representative cell may be used as thechannel quality of the RLC entity 2 c-10 (or the corresponding logicalchannel 2 c-20) (2 c-50). In FIG. 2C, it is assumed that cell 1 (2 c-30)is configured as a representative cell. Which cell will be therepresentative cell may be included in an RRC configuration message ofthe base station or may be configured according to a predetermined rule.For example, the cell having the lowest (or highest) cell index valueamong usable cells may be the representative cell. In this case, theusable cells may be configured cells or activated cells among theconfigured cells. The measurement value of the channel quality mentionedin FIG. 2C may include one of a RSRP, a RSRQ, a SINR, and a CQI. Also,the measurement value may be a value to which one or more of L1filtering or L3 filtering are applied.

FIG. 2D illustrates a method of calculating a measurement value of aradio bearer according to an embodiment of the disclosure.

Referring to FIG. 2D, the activation and deactivation of packetduplication transmission may be configured by the base station. However,the activation and deactivation of packet duplication transmission bythe base station may take a long time until the base station recognizesthe state change of the UE and issues an activation or deactivationcommand. In addition, an additional delay time may occur when the UEdoes not accurately receive a packet duplication activation ordeactivate command. In order to reduce this inefficiency, the UE mayspontaneously perform packet duplication transmission according to aconfigured or preconfigured rule. This rule may be due to the result ofmeasuring a cell usable by the radio bearer performing packetduplication transmission. FIG. 2D illustrates a method of defining ameasurement value of a radio bearer used to perform spontaneous packetduplication transmission of the UE. In FIG. 2D, it is assumed that aradio bearer 2 d-10 includes a total of three RLC entities such as anRLC 1 (2 d-30), an RLC 2 (2 d-40), and an RLC 3 (2 d-50), and a PDCP 2d-20. Also, the RLC 1 may correspond to a logical channel 1 (2 d-60),the RLC 2 may correspond to a logical channel 2 (2 d-70), and the RLC 3may correspond to a logical channel 3 (2 d-80). It is assumed that thelogical channel 1 (2 d-60) may use a cell 1 (2 d-90) and a cell 2 (2d-100), the logical channel 2 (2 d-70) may use a cell 4 (2 d-120), acell 5 (2 d-130), and a cell 6 (2 d-140), and the logical channel 3 (2d-80) may use a cell 8 (2 d-160). In this example, cell 3 (2 d-110) andcell 7 (2 d-150) are present, but unused.

A list of cells usable by each logical channel may be transmitted bybeing included in the logical channel configuration in an RRCconfiguration message that is transmitted from the base station to theUE. As described above, because the RLC entity and the logical channelmay have one-to-one correspondence with each other, a list of cellsusable by the logical channel may correspond to a list of cells usableby the RLC entity. Because the UE measures the channel quality of eachcell, a measurement value of the channel quality of the radio bearer maybe derived by using the measurement values of the cell usable in the RLCentity (the logical channel) configured in the radio bearer (2 d-200).In this case, the measurement value of the channel quality of the radiobearer may be one of the average value, the minimum value, the maximumvalue, and the median value of the measurement values of thecorresponding cells. In this case, the usable cells may be configuredcells or activated cells among the configured cells. The measurementvalue of the channel quality mentioned in FIG. 2D may include one of aRSRP, a RSRQ, a SINR, and a CQI. Also, the measurement value may be avalue to which one or more of L1 filtering or L3 filtering are applied.

FIG. 2E illustrates another method of calculating a measurement value ofa radio bearer according to an embodiment of the disclosure.

Referring to FIG. 2E, the activation and deactivation of packetduplication transmission may be configured by the base station. However,the activation and deactivation of packet duplication transmission bythe base station may take a long time until the base station recognizesthe state change of the UE and issues an activation or deactivationcommand. In addition, an additional delay time may occur when the UEdoes not accurately receive a packet duplication activation ordeactivate command. In order to reduce this inefficiency, the UE mayspontaneously perform packet duplication transmission according to aconfigured or preconfigured rule. This rule may be due to the result ofmeasuring a cell usable by the radio bearer performing packetduplication transmission. FIG. 2E illustrates a method of defining ameasurement value of a radio bearer used to perform spontaneous packetduplication transmission of the UE. In FIG. 2E, it is assumed that aradio bearer 2 e-10 includes a total of three RLC entities such as anRLC 1 (2 e-30), an RLC 2 (2 e-40), and an RLC 3 (2 e-50), and a PDCP 2e-20. Also, the RLC 1 (2 e-30) may correspond to a logical channel 1 (2e-60), the RLC 2 (2 e-40) may correspond to a logical channel 2 (2e-70), and the RLC 3 (2 e-50) may correspond to a logical channel 3 (2e-80). It is assumed that the logical channel 1 (2 e-60) may use a cell1 (2 e-90) and a cell 2 (2 e-100), the logical channel 2 (2 e-70) mayuse a cell 4 (2 e-120), a cell 5 (2 e-130), and a cell 6 (2 e-140), andthe logical channel 3 (2 e-80) may use a cell 8 (2 e-160). In thisexample, cell 3 (2 e-110) and cell 7 (2 e-150) are present, but unused.

A list of cells usable by each logical channel may be transmitted bybeing included in the logical channel configuration in an RRCconfiguration message that is transmitted from the base station to theUE. As described above, because the RLC entity and the logical channelmay have one-to-one correspondence with each other, a list of cellsusable by the logical channel may correspond to a list of cells usableby the RLC entity. Because the UE measures the channel quality of eachcell, a measurement value of the channel quality of the radio bearer maybe derived by using the measurement value of a representative cell amongthe cells usable in the RLC entity (the logical channel) configured inthe radio bearer (2 e-200). In FIG. 2E, it is assumed that cell 2 (2e-100) is configured as the representative cell. Which cell will be therepresentative cell may be included in an RRC configuration message ofthe base station or may be configured according to a predetermined rule.For example, the cell having the lowest (or highest) cell index valueamong usable cells may be the representative cell. In this case, theusable cells may be configured or preconfigured cells, or activatedcells among the configured of preconfigured cells. The measurement valueof the channel quality mentioned in FIG. 2E may include one of a RSRP, aRSRQ, a SINR, and a CQI. Also, the measurement value may be a value towhich one or more of L1 filtering or L3 filtering are applied.

FIG. 2F is a flowchart illustrating a method of a UE performingspontaneous packet duplication transmission according to an embodimentof the disclosure.

Referring to FIG. 2F, the UE may determine whether to perform packetduplication transmission by itself by using the measured value of theRLC entity described in FIG. 2B or 2C. When packet duplicationtransmission is configured in a certain radio bearer, the UE may performcalculation of the measurement values of RLC entities used for packetduplication transmission at operation 2 f-10. The calculation of themeasurement values may be the method described in FIG. 2B or 2C. In thiscase, it may be confirmed whether the measurement value of all RLCentities used for packet transmission in the radio bearer is less than,more than, or equal to a configured or preconfigured threshold value atoperation 2 f-20. However, according to an embodiment of the disclosure,it may be determined whether the measurement value is less than, morethan, or equal to a threshold value for some RLC entities among all ofthe configured RLC entities. When the measurement value of all RLCentities used for packet transmission in the radio bearer is less than,more than, or equal to a configured or preconfigured threshold value,the UE may perform packet duplication transmission at operation 2 f-30.When the measured value of the RLC entity does not satisfy the conditionof operation 2 f-20, packet duplication transmission may not beperformed at operation 2 f-40. That is, the UE may perform packetduplication transmission only when packet duplication transmission isrequired. Here, when the UE does not perform packet duplicationtransmission, the packet may be transmitted only to a preconfiguredprimary RLC entity or the packet may be transmitted to one RLC entityamong the configured RLC entities. When the packet duplicationtransmission is deactivated, when a split bearer operation should beperformed, threshold-based data transmission may be performed for theoperation of a split bearer by using one master cell group (MCG) RLC andone secondary cell group (SCG) RLC.

FIG. 2G is another flowchart illustrating a method of a UE performingspontaneous packet duplication transmission according to an embodimentof the disclosure.

Referring to FIG. 2G, the UE may determine whether to perform packetduplication transmission by itself by using the measured value of theRLC entity described in FIG. 2B or 2C. When packet duplicationtransmission is configured in a certain radio bearer, the UE may performcalculation of the measurement values of RLC entities used for packetduplication transmission at operation 2 g-10. The calculation of themeasurement values may be performed by using the method described inFIG. 2B or 2C. Also, the UE may determine whether the measurement valueof a particular RLC entity of the radio bearer is less than, more than,or equal to a configured or preconfigured threshold value at operation 2g-20. In this case, the particular RLC entity may be one of a primaryRLC entity or a secondary RLC entity. Also, when the measurement valueof a particular RLC entity of the radio bearer is less than, more than,or equal to a configured or preconfigured threshold value, the UE mayperform packet duplication transmission at operation 2 g-30. When themeasurement value of particular RLC entities does not satisfy thecondition of operation 2 g-20, the UE may not perform packet duplicationtransmission at operation 2 g-40. That is, the UE may perform packetduplication transmission only when packet duplication transmission isrequired. Here, when the UE does not perform packet duplicationtransmission, the packet may be transmitted only to a preconfiguredprimary RLC entity, the packet may be transmitted only to a particularRLC entity of the measurement value for determining packet duplicationtransmission specified in operation 2 g-20, or the packet may betransmitted to any one of the configured RLC entities. When the packetduplication transmission is deactivated, when a split bearer operationshould be performed, threshold-based data transmission may be performedfor the operation of a split bearer by using one MCG RLC and one SCGRLC.

FIG. 2H illustrates a method of configuring spontaneous packetduplication transmission of a UE according to an embodiment of thedisclosure.

Referring to FIG. 2H, a base station 2 h-10 may configure a radio bearerfor performing packet duplication transmission to a UE 2 h-20 through anRRC configuration (2 h-30) or a reconfiguration message (notillustrated). In this case, the base station 2 h-10 may configurewhether to perform spontaneous packet duplication of the UE 2 h-20 foreach radio bearer. In addition, the base station 2 h-10 may also notifywhether spontaneous packet duplication transmission will be performedunder a certain condition. The condition in which packet duplicationtransmission is performed may be determined based on the abovemeasurement value of the RLC entity or the measurement value of theradio bearer. After receiving an RRC configuration or reconfigurationmessage (not illustrated) from the base station 2 h-10, the UE 2 h-20may transmit an RRC configuration or reconfiguration completion messageto the base station 2 h-10 (2 h-40).

FIG. 2I illustrates a procedure of notifying a packet duplicationactivation state of a UE according to an embodiment of the disclosure.

Referring to FIG. 2I, when a UE 2 i-10 has activated or deactivatedpacket duplication transmission under a configured or preconfiguredcondition or the like, a process of notifying the same to a base station2 i-20 may be necessary. When the configured or preconfigured packetduplication transmission condition is satisfied (2 i-30), the UE 2 i-10may notify the base station 2 i-20 that spontaneous packet duplicationtransmission of the UE 2 i-10 has started (2 i-40) and perform packetduplication transmission (2 i-50). In this case, a message indicatingthat the spontaneous packet duplication transmission has been performedmay include a radio bearer ID to indicate in which radio bearer thepacket duplication transmission is being performed. According to anembodiment of the disclosure, a message indicating that the packetduplication transmission has been performed may include a logicalchannel identifier corresponding to an RLC entity to indicate the RLCentity in which the packet duplication transmission is being performed.Also, the message indicating that packet duplication transmission hasbeen performed may include information indicating which packetduplication transmission condition has been satisfied or may include themeasurement result of each RLC entity or the measurement result of theradio bearer. In the embodiment of FIG. 2I, the packet duplicationnotification (2 i-40) and packet duplication performance (2 i-50) may bestarted at the same time or may be performed sequentially at similartimes.

When satisfying the packet duplication transmission stop condition (2i-60) while performing packet duplication transmission (2 i-50), the UEmay transmit a packet duplication stop notification message to the basestation (2 i-70) and may no longer perform packet duplicationtransmission (2 i-80). Here, the packet duplication transmission stopcondition (2 i-60) may be the opposite condition of the packetduplication transmission condition (2 i-30) or may be anotherpreconfigured condition. A message (2 i-70) indicating that spontaneouspacket duplication transmission has been stopped may include a radiobearer ID to indicate in which radio bearer the packet duplicationtransmission is stopped. According to an embodiment of the disclosure,the message may include a logical channel identifier corresponding to anRLC entity to notify the RLC entity in which the packet duplicationtransmission is being performed or is stopped. Also, the message mayinclude information indicating which packet duplication transmissionstop condition has been satisfied or may include the measurement resultof each RLC entity or the measurement result of the radio bearer. InFIG. 2I, the packet duplication stop notification (2 i-70) and thepacket duplication non-performance operation (2 i-80) may be started atthe same time or may be performed sequentially at similar times.

FIG. 2J illustrates a procedure of triggering a regular buffer statusreport (BSR) according to spontaneous packet duplication activation of aUE according to an embodiment of the disclosure.

Referring to FIG. 2J, when a UE 2 j-10 has activated or deactivatedpacket duplication transmission under a configured or preconfiguredcondition or the like, a process of requesting a base station 2 j-20 toallocate a radio resource for packet duplication transmission may benecessary. When the UE 2 j-10 satisfies the preconfigured packetduplication transmission condition (2 j-30), the UE 2 j-10 may trigger aregular buffer status report (BSR) to transmit a regular BSR to the basestation 2 j-20 (2 j-40) and perform packet duplication transmission (2j-50). In FIG. 2J, the triggering and transmission of the regular BSR (2j-40) and the packet duplication performance (2 j-50) may be started atthe same time or may be performed sequentially at similar times.Thereafter, when the UE 2 j-10 satisfies a packet duplicationtransmission stop condition (2 j-60) while performing packet duplicationtransmission (2 j-50), the UE 2 j-10 may trigger a regular BSR andtransmit the regular BSR to the base station 2 j-20 (2 j-70) in order tonotify the base UE 2 j-20 that the allocation of a radio resource forpacket duplication transmission is no longer required and may no longerperform packet duplication transmission (2 j-80). Here, the packetduplication transmission stop condition (2 i-60) may be the oppositecondition of the packet duplication transmission condition (2 i-30) ormay be another configured or preconfigured condition. In FIG. 2J, thetriggering and transmission of the regular BSR (2 j-70) and the packetduplication non-performance operation (2 j-80) may be started at thesame time or may be performed sequentially at similar times.

FIG. 2K is a flowchart illustrating a method of a UE performingspontaneous packet duplication transmission according to an embodimentof the disclosure.

Referring to FIG. 2K, the UE may determine whether to perform packetduplication transmission by itself by using the measurement value of theradio bearer described above. When packet duplication transmission isconfigured in a certain radio bearer, the UE may perform calculation ofthe measurement value of the radio bearer in which the packetduplication transmission is configured at operation 2 k-10. Theabove-described method may be used for the calculation of themeasurement value. In this case, the UE may determine whether themeasurement value of the radio bearer is less than, more than, or equalto a configured or preconfigured threshold value at operation 2 k-20.Also, when the measurement value of the radio bearer is less than, morethan, or equal to a configured or preconfigured threshold value, the UEmay perform packet duplication transmission at operation 2 k-30. Whenthe measured value of the radio bearer does not satisfy the condition ofoperation 2 k-20, packet duplication transmission may not be performedat operation 2 k-40. That is, the UE may perform packet duplicationtransmission only when packet duplication transmission is required.Here, when the UE does not perform packet duplication transmission, thepacket may be transmitted only to a preconfigured primary RLC entity orthe packet may be transmitted to any one RLC entity among the configuredRLC entities. When the packet duplication transmission is deactivated,when a split bearer operation should be performed, threshold-based datatransmission may be performed for the operation of a split bearer byusing one MCG RLC and one SCG RLC.

FIG. 2L illustrates a split bearer operation when packet duplicationtransmission is deactivated according to an embodiment of thedisclosure.

Referring to FIG. 2L, an embodiment of FIG. 2L may be applicable notonly for spontaneous packet duplication transmission of the UE, but alsofor deactivation of packet duplication transmission under the control ofthe base station. Referring to FIG. 2L, it is assumed that a radiobearer 2 l-10 includes a total of four RLC entities 2 l-20, 2 l-30, 2l-40, and 2 l-50 configured for the radio bearer 2 l-10 in which packetduplication is configured, and a PDCP 2 l-15. It is assumed that amongthem, the RLC 1 (2 l-20) and the RLC 2 (2 l-30) are an MCG RLC (2 l-60)configured in the MCG, and the RLC 3 (2 l-40) and the RLC 4 (2 l-50) arean SCG RLC (2 l-70) configured in the SCG. When the packet duplicationtransmission is deactivated (2 l-80), the corresponding radio bearer mayreturn to a split bearer operation. Here, the split bearer may mean aradio bearer including one MCG RLC and one SCG RLC. Thus, one MCG RLCand one SCG RLC should be selected.

For this purpose, a primary RLC 2 l-120 and a secondary RLC 2 l-140 maybe configured. The primary RLC 2 l-120 may mean an RLC entity that mayalways be used for packet transmission. The secondary RLC 2 l-140 maymean an RLC entity that is used for transmission when there is data morethan or equal to a threshold value of the split bearer. Other RLCentities other than the primary RLC entity 2 l-120 or the secondary RLCentity 2 l-140 may not be used for packet transmission when the packetduplication transmission is deactivated. The primary RLC 2 l-120 and thesecondary RLC 2 l-140 may be RLC entities belonging to different cellgroups. The primary RLC 2 l-120 and the secondary RLC 2 l-140 may beconfigured at the time of RRC configuration from the base station or maybe configured according to a predetermined rule. When the RLC entity isnot configured at the time of RRC configuration from the base station,the primary RLC 2 l-120 and the secondary RLC 2 l-140 may be configuredin ascending order (or descending order) of logical channel identifiervalues. According to an embodiment of the disclosure, an RLC entitycapable of using a PCell or a PSCell may be configured as the primaryRLC 2 l-120 or the secondary RLC 2 l-140. Also, an RLC entity that isnot used for a split bearer operation although configured as an RLCentity may be referred to as a secondary RLC.

FIG. 2M is a block diagram illustrating a structure of a base stationaccording to an embodiment of the disclosure.

Referring to FIG. 2M, the base station may include a transceiver 2 m-10,a base station controller 2 m-20, and storage 2 m-30. In the disclosure,the base station controller 2 m-20 may be defined as a circuit, anapplication-specific integrated circuit, or at least one processor.

The transceiver 2 m-10 may exchange signals with other network entities.For example, the transceiver 2 m-10 may transmit system information tothe UE and may transmit a synchronization signal or a reference signaltherefrom.

The base station controller 2 m-20 may control overall operations of thebase station according to an embodiment of the disclosure. For example,the base station controller 2 m-20 may control a signal flow between therespective blocks to perform an operation according to the flowchartsdescribed above. According to an embodiment of the disclosure, the basestation controller 2 m-20 may configure a radio bearer for performingpacket duplication transmission to the UE and may control the componentof the base station to indicate whether the UE will perform spontaneouspacket duplication transmission under a certain condition.

The storage 2 m-30 may store at least one of information transmitted orreceived through the transceiver 2 m-10 or information generated throughthe base station controller 2 m-20.

FIG. 2N is a block diagram illustrating a structure of a UE according toan embodiment of the disclosure.

Referring to FIG. 2N, the UE may include a transceiver 2 n-10, aterminal controller 2 n-20, and storage 2 n-30. In the disclosure, theterminal controller 2 n-20 may be defined as a circuit, anapplication-specific integrated circuit, or at least one processor.

The transceiver 2 n-10 may exchange signals with other network entities.For example, the transceiver 2 n-10 may receive system information fromthe base station and may receive a synchronization signal or a referencesignal therefrom.

The terminal controller 2 n-20 may control an overall operation of theUE according to an embodiment of the disclosure. For example, theterminal controller 2 n-20 may control a signal flow between therespective blocks to perform an operation according to the flowchartdescribed above. According to an embodiment of the disclosure, theterminal controller 2 n-20 may perform calculation of a measurementvalue of a radio bearer in which packet duplication transmission isconfigured and may control the components of the UE to perform or not toperform packet duplication transmission based on the measurement value.

The storage 2 n-30 may store at least one of information transmitted orreceived through the transceiver 2 n-10 or information generated throughthe terminal controller 2 n-20.

The methods according to the embodiments of the disclosure described inthe specification or the claims may be implemented by hardware,software, or a combination thereof.

When the methods are implemented by software, a non-transitorycomputer-readable storage medium or a computer program product may beprovided to store one or more programs (software modules). The one ormore programs stored in the computer-readable storage medium or thecomputer program product may be configured for execution by one or moreprocessors in an electronic device. The one or more programs may includeinstructions for causing the electronic device to execute the methodsaccording to the embodiments of the disclosure described in thespecification or the claims.

These programs (software modules or software) may be stored in randomaccess memories (RAMs), nonvolatile memories including flash memories,read only memories (ROMs), electrically erasable programmable ROMs(EEPROMs), magnetic disc storage devices, compact disc-ROMs (CD-ROMs),digital versatile discs (DVDs), other types of optical storage devices,or magnetic cassettes. Also, the programs may be stored in a memoryconfigured by a combination of some or all of such storage devices.Also, each of the memories may be provided in plurality.

The programs may be stored in an attachable storage device that may beaccessed through a communication network such as Internet, Intranet,local area network (LAN), wide LAN (WLAN), or storage area network(SAN), or through a communication network configured by any combinationthereof. Such a storage device may be connected through an external portto an apparatus performing an embodiment of the disclosure. Also, aseparate storage device on a communication network may be connected toan apparatus performing an embodiment of the disclosure.

In the above particular embodiments of the disclosure, the componentsincluded in the disclosure are expressed as singular or plural accordingto the presented particular embodiments of the disclosure. However, thesingular or plural expressions are selected according to the presentedsituations for convenience of description, and the disclosure is notlimited to the singular or plural components. The components expressedin the plural may even be configured in the singular or the componentsexpressed in the singular may even be configured in the plural.

The described embodiments provide apparatuses and methods capable ofeffectively providing services in wireless communication systems.

It should be understood that the embodiments of the disclosure describedherein should be considered in a descriptive sense only, and not forpurposes of limitation. Also, the embodiments of the disclosure may beoperated in combination when necessary. For example, portions of anembodiment and another embodiment of the disclosure may be combined witheach other. Also, embodiments of the disclosure may be implemented inother systems such as LTE systems, 5G or NR systems, and othermodifications may be made therein based on the spirit of the aboveembodiments of the disclosure.

While the disclosure has been shown and described with reference tovarious embodiments thereof, it will be understood by those skilled inthe art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the disclosure as definedby the appended claims and their equivalents.

What is claimed is:
 1. A method performed by a user equipment (UE) in awireless communication system, the method comprising: receiving a radioresource control (RRC) configuration information indicating a secondaryradio link control (RLC) entity for returning to a split beareroperation; and in case that a packet duplication is deactivated and apacket data convergence protocol (PDCP) entity of the UE is associatedwith more than two RLC entities, identifying the secondary RLC entityindicated by the RRC configuration information from the more than twoRLC entities and performing the split bearer operation using a primaryRLC entity and the secondary RLC entity, wherein the split beareroperation includes: in case that an amount of data for the primary RLCentity and the secondary RLC entity is equal to or larger than athreshold related to the split bearer operation, transmitting a PDCPpacket data unit (PDU) using the secondary RLC entity, and wherein theprimary RLC entity is an RLC entity belonging to a cell group differentfrom a cell group of the secondary RLC entity.
 2. The method of claim 1,further comprising: in case that the amount of the data for the primaryRLC entity and the secondary RLC entity is less than the thresholdrelated to the split bearer operation, transmitting the PDCP PDU usingthe primary RLC entity.
 3. The method of claim 1, wherein the RRCconfiguration information further indicates the primary RLC entity. 4.The method of claim 1, wherein the primary RLC entity is associated witha master cell group (MCG) and the secondary RLC entity is associatedwith a secondary cell group (SCG).
 5. The method of claim 1, furthercomprising: performing the packet duplication using at least two RLCentities among the more than two RLC entities.
 6. A user equipment (UE)configured to operate in a wireless communication system, the UEcomprising: a transceiver; and at least one processor coupled to thetransceiver and configured to: receive a radio resource control (RRC)configuration information indicating a secondary radio link control(RLC) entity for returning to a split bearer operation, and in case thata packet duplication is deactivated and a packet data convergenceprotocol (PDCP) entity of the UE is associated with more than two RLCentities, identify the secondary RLC entity indicated by the RRCconfiguration information from the more than two RLC entities andperform the split bearer operation using a primary RLC entity and thesecondary RLC entity, wherein the split bearer operation includes: incase that an amount of data for the primary RLC entity and the secondaryRLC entity is equal to or larger than a threshold related to the splitbearer operation, transmit a PDCP packet data unit (PDU) using thesecondary RLC entity, and wherein the primary RLC entity is an RLCentity belonging to a cell group different from a cell group of thesecondary RLC entity.
 7. The UE of claim 6, wherein the at least oneprocessor is further configured to: in case that the amount of the datafor the primary RLC entity and the secondary RLC entity is less than thethreshold related to the split bearer operation, transmit the PDCP PDUusing the primary RLC entity.
 8. The UE of claim 6, wherein the RRCconfiguration information further indicates the primary RLC entity. 9.The UE of claim 6, wherein the primary RLC entity is associated with amaster cell group (MCG) and the secondary RLC entity is associated witha secondary cell group (SCG).
 10. The UE of claim 6, wherein the atleast one processor is further configured to: perform the packetduplication using at least two RLC entities among the more than two RLCentities.
 11. A method performed by a packet data convergence protocol(PDCP) entity of a base station in a wireless communication system, themethod comprising: receiving, from a radio resource control (RRC)entity, information indicating a secondary radio link control (RLC)entity for returning to a split bearer operation; and in case that apacket duplication is deactivated and the PDCP entity is associated withmore than two RLC entities, identifying the secondary RLC entityindicated by the information from the more than two RLC entities andperforming the split bearer operation using a primary RLC entity and thesecondary RLC entity, wherein the split bearer operation includes: incase that an amount of data for the primary RLC entity and the secondaryRLC entity is equal to or larger than a threshold related to the splitbearer operation, transmitting a PDCP packet data unit (PDU) using thesecondary RLC entity, and wherein the primary RLC entity is an RLCentity belonging to a cell group different from a cell group of thesecondary RLC entity.
 12. The method of claim 11, further comprising: incase that the amount of the data for the primary RLC entity and thesecondary RLC entity is less than the threshold related to the splitbearer operation, transmitting the PDCP PDU using the primary RLCentity.
 13. The method of claim 11, wherein the information receivedfrom the RRC entity further indicates the primary RLC entity.
 14. Themethod of claim 11, wherein the primary RLC entity is associated with amaster cell group (MCG) and the secondary RLC entity is associated witha secondary cell group (SCG).
 15. The method of claim 11, furthercomprising: performing the packet duplication using at least two RLCentities among the more than two RLC entities.
 16. A base stationconfigured to operate in a wireless communication system, the basestation comprising: a transceiver; and at least one processor coupled tothe transceiver and configured to: receive, from a radio resourcecontrol (RRC) entity, information indicating a secondary radio linkcontrol (RLC) entity for returning to a split bearer operation, and incase that a packet duplication is deactivated and a packet dataconvergence protocol (PDCP) entity of the base station is associatedwith more than two RLC entities, identify the secondary RLC entityindicated by the information from the more than two RLC entities andperforming the split bearer operation using a primary RLC entity and thesecondary RLC entity, wherein the split bearer operation includes: incase that an amount of data for the primary RLC entity and the secondaryRLC entity is equal to or larger than a threshold related to the splitbearer operation, transmit a PDCP packet data unit (PDU) using thesecondary RLC entity, and wherein the primary RLC entity is an RLCentity belonging to a cell group different from a cell group of thesecondary RLC entity.
 17. The base station of claim 16, wherein the atleast one processor is further configured to: in case that the amount ofthe data for the primary RLC entity and the secondary RLC entity is lessthan the threshold related to the split bearer operation, transmit thePDCP PDU using the primary RLC entity.
 18. The base station of claim 16,wherein the information received from the RRC entity further indicatesthe primary RLC entity.
 19. The base station of claim 16, wherein theprimary RLC entity is associated with a master cell group (MCG) and thesecondary RLC entity is associated with a secondary cell group (SCG).20. The base station of claim 16, wherein the at least one processor isfurther configured to: perform the packet duplication using at least twoRLC entities among the more than two RLC entities.